Bottom Line:
The antioxidant activity efficiency correlated with the number and position of hydroxyl groups.The most effective antioxidants were resveratrol analogs containing three hydroxyl groups in the benzylidene part of their molecules.These results provide new insights into the relationship between the chemical structure and biological activity of resveratrol analogs.

ABSTRACTResveratrol (3,5,4'-trihydroxystilbene) is a phytoalexin produced by plants. Resveratrol is known for its anti-cancer, antiviral and antioxidant properties. We prepared imine analogs of resveratrol ((hydroxyphenyliminomethyl)phenols) and tested their antioxidant activity. All prepared resveratrol analogs were able to scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH), galvinoxyl radical (GOR) and 2,2'-azino-bis(3-ethylbenzothiazoline)-6-sulphonic acid (ABTS) radicals. The antioxidant activity efficiency correlated with the number and position of hydroxyl groups. The most effective antioxidants were resveratrol analogs containing three hydroxyl groups in the benzylidene part of their molecules. These results provide new insights into the relationship between the chemical structure and biological activity of resveratrol analogs.

Mentions:
To test this assumption we performed the following experiment. According to the work of Cigáň et al. [32], creation of self-aggregates can be determined from concentration-dependence of absorption or fluorescence spectra. The formation of self-aggregates should be manifested by a shift of emission maxima or by a shape change in absorption/fluorescence spectra with an increase of concentration of the studied compound. We observed that the corresponding changes in absorption spectra were very small. Also in fluorescence emission spectra, relatively small batochromic shifts were observed with increasing concentrations. Compound 5 with lower antioxidant activity exhibited approximately 11 nm, whereas compound 14 with higher antioxidant activity showed only 4 nm (data not shown). The formation of self-aggregates was apparent from the fluorescence excitation spectra. We observed changes in shapes of these spectra with the increasing concentrations of (Hydroxyphenyliminomethyl)phenols (Figure 3). These results suggest that one possible explanation for the lower antioxidant activity of some of the studied (Hydroxyphenyliminomethyl)phenols is formation of self-aggregates. A possible structure of aggregates for compound 3 is presented in Figure S1.

Mentions:
To test this assumption we performed the following experiment. According to the work of Cigáň et al. [32], creation of self-aggregates can be determined from concentration-dependence of absorption or fluorescence spectra. The formation of self-aggregates should be manifested by a shift of emission maxima or by a shape change in absorption/fluorescence spectra with an increase of concentration of the studied compound. We observed that the corresponding changes in absorption spectra were very small. Also in fluorescence emission spectra, relatively small batochromic shifts were observed with increasing concentrations. Compound 5 with lower antioxidant activity exhibited approximately 11 nm, whereas compound 14 with higher antioxidant activity showed only 4 nm (data not shown). The formation of self-aggregates was apparent from the fluorescence excitation spectra. We observed changes in shapes of these spectra with the increasing concentrations of (Hydroxyphenyliminomethyl)phenols (Figure 3). These results suggest that one possible explanation for the lower antioxidant activity of some of the studied (Hydroxyphenyliminomethyl)phenols is formation of self-aggregates. A possible structure of aggregates for compound 3 is presented in Figure S1.

Bottom Line:
The antioxidant activity efficiency correlated with the number and position of hydroxyl groups.The most effective antioxidants were resveratrol analogs containing three hydroxyl groups in the benzylidene part of their molecules.These results provide new insights into the relationship between the chemical structure and biological activity of resveratrol analogs.

ABSTRACTResveratrol (3,5,4'-trihydroxystilbene) is a phytoalexin produced by plants. Resveratrol is known for its anti-cancer, antiviral and antioxidant properties. We prepared imine analogs of resveratrol ((hydroxyphenyliminomethyl)phenols) and tested their antioxidant activity. All prepared resveratrol analogs were able to scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH), galvinoxyl radical (GOR) and 2,2'-azino-bis(3-ethylbenzothiazoline)-6-sulphonic acid (ABTS) radicals. The antioxidant activity efficiency correlated with the number and position of hydroxyl groups. The most effective antioxidants were resveratrol analogs containing three hydroxyl groups in the benzylidene part of their molecules. These results provide new insights into the relationship between the chemical structure and biological activity of resveratrol analogs.